001/*
002 * (C) Copyright 2015 Nuxeo SA (http://nuxeo.com/) and others.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 *
016 * Contributors:
017 * Nuxeo - initial API and implementation
018 */
019
020package org.nuxeo.ecm.platform.rendition.lazy;
021
022import java.security.MessageDigest;
023import java.security.NoSuchAlgorithmException;
024import java.util.ArrayList;
025import java.util.Calendar;
026import java.util.List;
027
028import org.apache.commons.logging.Log;
029import org.apache.commons.logging.LogFactory;
030import org.nuxeo.ecm.core.api.Blob;
031import org.nuxeo.ecm.core.api.DocumentModel;
032import org.nuxeo.ecm.core.api.NuxeoException;
033import org.nuxeo.ecm.core.api.impl.blob.StringBlob;
034import org.nuxeo.ecm.core.transientstore.api.TransientStore;
035import org.nuxeo.ecm.core.transientstore.api.TransientStoreService;
036import org.nuxeo.ecm.core.work.api.Work;
037import org.nuxeo.ecm.core.work.api.WorkManager;
038import org.nuxeo.ecm.platform.rendition.Rendition;
039import org.nuxeo.ecm.platform.rendition.extension.AutomationRenderer;
040import org.nuxeo.ecm.platform.rendition.extension.RenditionProvider;
041import org.nuxeo.ecm.platform.rendition.impl.LazyRendition;
042import org.nuxeo.ecm.platform.rendition.service.RenditionDefinition;
043import org.nuxeo.runtime.api.Framework;
044
045/**
046 * Default implementation of an asynchronous {@link RenditionProvider}
047 *
048 * @author <a href="mailto:tdelprat@nuxeo.com">Tiry</a>
049 * @since 7.2
050 */
051public abstract class AbstractLazyCachableRenditionProvider implements RenditionProvider {
052
053    public static final String WORKERID_KEY = "workerid";
054
055    public static final String CACHE_NAME = "LazyRenditionCache";
056
057    protected static Log log = LogFactory.getLog(AbstractLazyCachableRenditionProvider.class);
058
059    @Override
060    public List<Blob> render(DocumentModel doc, RenditionDefinition def) {
061
062        // build the key
063        String key = buildRenditionKey(doc, def);
064
065        // see if rendition is already in process
066
067        TransientStoreService tss = Framework.getService(TransientStoreService.class);
068
069        TransientStore ts = tss.getStore(CACHE_NAME);
070
071        if (ts == null) {
072            throw new NuxeoException("Unable to find Transient Store  " + CACHE_NAME);
073        }
074
075        if (!ts.exists(key)) {
076            Work work = getRenditionWork(key, doc, def);
077            ts.putParameter(key, WORKERID_KEY, work.getId());
078            List<Blob> blobs = new ArrayList<Blob>();
079            StringBlob emptyBlob = new StringBlob("");
080            emptyBlob.setFilename("inprogress");
081            emptyBlob.setMimeType("text/plain;" + LazyRendition.EMPTY_MARKER);
082            blobs.add(emptyBlob);
083            ts.putBlobs(key, blobs);
084            Framework.getService(WorkManager.class).schedule(work);
085        } else {
086            ts.release(key);
087        }
088
089        return ts.getBlobs(key);
090     }
091
092    @Override
093    public String getVariant(DocumentModel doc, RenditionDefinition definition) {
094        return AutomationRenderer.getVariant(doc, definition);
095    }
096
097    protected String buildRenditionKey(DocumentModel doc, RenditionDefinition def) {
098
099        StringBuffer sb = new StringBuffer(doc.getId());
100        sb.append("::");
101        String modificationDatePropertyName = def.getSourceDocumentModificationDatePropertyName();
102        Calendar modif = (Calendar) doc.getPropertyValue(modificationDatePropertyName);
103        if (modif != null) {
104            sb.append(modif.getTimeInMillis());
105            sb.append("::");
106        }
107        String variant = getVariant(doc, def);
108        if (variant != null) {
109            sb.append(variant);
110            sb.append("::");
111        }
112        sb.append(def.getName());
113
114        return getDigest(sb.toString());
115    }
116
117    protected String getDigest(String key) {
118        MessageDigest digest;
119        try {
120            digest = MessageDigest.getInstance("MD5");
121        } catch (NoSuchAlgorithmException e) {
122            return key;
123        }
124        byte[] buf = digest.digest(key.getBytes());
125        return toHexString(buf);
126    }
127
128    private static final char[] HEX_DIGITS = "0123456789abcdef".toCharArray();
129
130    protected String toHexString(byte[] data) {
131        StringBuilder buf = new StringBuilder(2 * data.length);
132        for (byte b : data) {
133            buf.append(HEX_DIGITS[(0xF0 & b) >> 4]);
134            buf.append(HEX_DIGITS[0x0F & b]);
135        }
136        return buf.toString();
137    }
138
139    /**
140     * Return the {@link Work} that will compute the {@link Rendition}. {@link AbstractRenditionBuilderWork} can be used
141     * as a base class
142     *
143     * @param key the key used to rendition
144     * @param doc the target {@link DocumentModel}
145     * @param def the {@link RenditionDefinition}
146     * @return
147     */
148    protected abstract Work getRenditionWork(final String key, final DocumentModel doc, final RenditionDefinition def);
149
150}